Currently, navigation systems on machines use inertial measurement units along with magnetometers for providing positioning/navigation data to the navigation systems. The magnetometers provide orientation data related to the machine to the navigation systems. The magnetometers are influenced by static and/or dynamic interferences such as iron distortions present around the magnetometer such as metal platforms, electrical circuits, other ferrous objects present on as well as around the machine, and so on. This may lead to errors in outputs of the magnetometers.
Errors due to static and/or dynamic interferences on the magnetometer are usually compensated by known calibration methods. But, for machines having a moving implement, a make-up of iron around the magnetometer may change dynamically based on the position of the implement with respect to the machine. The known calibration methods for static and/or dynamic interferences may be unable to provide compensation for such dynamic interferences due to the moving implement and calibrate the magnetometers accordingly. As a result, the magnetometer may be unable to provide accurate orientation data leading to errors in the positioning of the machine determined by the navigation system.
European Patent Application Number 2,677,275 discloses a method for compensating for soft iron magnetic disturbances in a heading reference system. The system includes a heading gyro disposed along a heading measurement axis. The system includes a magnetometer coupled to the heading gyro for providing an accurate heading relative to magnetic north. The method includes detecting changes in the magnetometer due to soft iron magnetic disturbances during a detection period for providing a first detected magnitude of change. The method includes detecting changes in the gyro heading relative to magnetic north during the detection period for providing a second detected magnitude of change. The method includes comparing the first and second detected magnitude of changes for providing a potential difference value of change. The method includes providing a predetermined acceptable threshold value of change. The method also includes determining if the potential difference value of change exceeds the predetermined acceptable threshold value of change. The method further includes providing a heading correction value to the heading reference system when the potential difference value of change exceeds the acceptable threshold value of change for enabling adjustment of the gyro heading to maintain the accurate heading in the face of the soft iron magnetic disturbances.
However, the '275 Patent Application does not disclose a method for compensating the soft iron magnetic disturbances caused due to a moving implement in a machine. Hence, there is a need for an improved navigation system for machines having the movable implement installed thereon.